Semiconductor structure having an active device and method for manufacturing and manipulating the same

ABSTRACT

A semiconductor structure comprising a substrate, an active device, a field oxide layer and a poly-silicon resistor is disclosed. The active device is formed in a surface area of the substrate. The active device has a first doped area, a second doped area and a third doped area. The second doped area is disposed on the first doped area. The first doped area is between the second and the third doped areas. The first doped area has a first type conductivity. The third doped area has a second type conductivity. The first and the second type conductivities are different. The field oxide layer is disposed on a part of the third doped area. The poly-silicon resistor is disposed on the field oxide layer and is electrically connected to the third doped area.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates in general to a semiconductor device, and methodfor manufacturing and manipulating the same, and more particularly to asemiconductor device having a combination of an active device and apoly-silicon resistor, and method for manufacturing and manipulating thesame.

2. Description of the Related Art

Recently, green power industries are emphasized. The green powerindustry require higher conversion efficiency and lower standby powerconsumption. The high voltage process has been widely used for powermanagement integrated circuit (PMIC) and switch mode power supplies(SMPS). SMPS have start-up circuit which requires a wide range of higherinput voltage (such as a voltage from 40 Volt to 750 Volt).

The switch mode power IC requires to integrate a start-up circuit and apulse width modulation (PWM) circuit. Generally, a start-up circuit of ahigh voltage device utilizes a resistor for providing a charging currentto a capacitor. The start-up circuit stops working until the voltage ofthe capacitor reaches a start-up voltage of the PWM circuit.Conventionally, a power resistor is utilized in a traditional highvoltage start-up circuit. Therefore, power would be continuouslyconsumed by the power resistor, even though the start-up circuit stopsworking. Thus, the traditional high voltage start-up circuit can notachieve an energy saving effect.

SUMMARY OF THE INVENTION

The invention is directed to a semiconductor structure and method formanufacturing and manipulating the same. The semiconductor structurecombines an active device and a poly-silicon resistor so that a resultof volume reduction can be achieved. Besides, the semiconductorstructure can be produced easily without additional complex process.

According to one aspect of the present invention, a semiconductorstructure comprising a substrate, an active device, a field oxide layerand a poly-silicon resistor is disclosed. The active device is formed ina surface area of the substrate. The active device has a first dopedarea, a second doped area and a third doped area. The second doped areais disposed on the first doped area. The first doped area is between thesecond and the third doped areas. The first doped area has a first typeconductivity. The third doped area has a second type conductivity. Thefirst and the second type conductivities are different. The field oxidelayer is disposed on a part of the third doped area. The poly-siliconresistor is disposed on the field oxide layer and is electricallyconnected to the third doped area.

According to a another aspect of the present invention, a method ofmanufacturing a semiconductor structure is disclosed. The methodcomprises following steps. A substrate is provided. An active device ina surface area of the substrate is formed. The active device has a firstdoped area, a second doped area and a third doped area. The second dopedarea is disposed on the first doped area, the first doped area isdisposed between the second and the third doped area. The first dopedarea has a first type conductivity, the third doped area has a secondtype conductivity, the first type conductivity and the second typeconductivity are different. A field oxide layer on a part of the thirddoped area is formed. A poly-silicon resistor on the field oxide layeris formed, and the poly-silicon resistor and the third doped area areelectrically connected.

According to still another aspect of the present invention, a method ofmanipulating a semiconductor structure is disclosed. The semiconductorstructure comprises a substrate, an active device, a field oxide layerand a poly-silicon resistor. The active device comprises a gate, a drainand a source. The field oxide layer is disposed on a part of the activedevice. The poly-silicon resistor comprises a plurality of electricalconnecting terminals. The method comprises following steps. A gatevoltage to the gate is applied, a drain voltage to the drain is appliedand a source voltage to the source is applied. One of the electricalconnecting terminals to the drain is coupled. Another one of theelectrical connecting terminals to a reference voltage is coupled. Stillanother one of the electrical connecting terminals to a ground terminalis coupled. A voltage potential difference exist between the another oneof the electrical connecting terminals and the still another one of theelectrical connecting terminals.

The above and other aspects of the invention will become betterunderstood with regard to the following detailed description of thepreferred but non-limiting embodiment(s). The following description ismade with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 are cross-sectional views showing a semiconductor structureaccording to one embodiment.

FIGS. 2A˜2E are top views of different semiconductor structuresembodiment for according to FIG. 1 of the invention.

FIG. 3 shows another semiconductor structure according to another oneembodiment.

FIG. 4 shows still another semiconductor structure according to stillanother one embodiment.

DETAILED DESCRIPTION OF THE INVENTION First Embodiment

FIG. 1 illustrates a semiconductor structure according to one embodimentof the invention. Referring to FIG. 1, the semiconductor structure 10comprises a substrate 100, an active device 103 formed in a surface areaof the substrate 100, such as a silicon substrate. The substrate 100 hasa first conductivity, for example a p type conductivity. The activedevice 103 has a doped area 106 a, a doped area 106 b, a doped area 107,a plurality of doped areas 108 a, a doped area 108 b, a doped area 110,a doped area 112, a doped area 114, a doped area 116, a doped area 118and a doped area 120. The doped area 116 is disposed on the doped area106 a. The doped area 106 a is disposed between the doped area 107 andthe doped area 116.

The doped area 106 a, the doped area 106 b, the doped area 112, thedoped area 116 and the doped area 120 have a first type conductivity,the doped area 107, the doped areas 108 a, the doped area 108 b, thedoped area 110, the doped area 114 and the doped area 118 have a secondtype conductivity, the first type and the second type conductivities aredifferent. For example, the first type conductive doped area are dopedwith p type conductive ions such as boron. The second type conductivedoped area are doped with n type conductive ions such as arsenic orphosphorus.

In one embodiment, the doped area 114, the doped area 116, the dopedarea 118 and the doped area 120 are heavily doped areas having heavilydoped ions. The doped area 106 a, the doped area 106 b, the doped area107, the doped areas 108 a and the doped area 108 b are lightly dopedareas having light doped ions. In one embodiment, the doped area 106 aand the doped area 106 b are wells having a first type conductivity,such as p type wells. The doped area 107 is a high voltage well, such asa high voltage n type well. The doped areas 108 a and the doped area 108b are deep well, such as a n type deep well. The doped areas 108 a andthe doped area 108 b are disposed adjacent to the doped area 106 a. Forexample, the doped areas 108 a and the doped area 108 b are disposed ata bottom side and a lateral side of the doped area 106 a, respectively.The doped areas 108 a and the doped area 108 b have the secondconductivity. A distance between the doped areas 108 a and a number ofthe doped areas 108 a are related to a pinch-off voltage of the activedevice 103. A distance between two doped areas 108 a and a distancebetween the doped areas 108 a and the doped area 108 b are related tothe pinch-off voltage of the active device 103.

The doped area 110 and the doped area 112 are formed in the doped area107. The doped area 110 is for example a first top doped area and thedoped area 112 is for example a second top doped area. The conductivityof the first and the second doped area are different. In one embodiment,the doped area 110 has a second type conductivity and the doped area 112has a first type conductivity. In another embodiment, the doped area 110has a first type conductivity and the doped area 112 has a second typeconductivity. In one embodiment, the doped area 114 in FIG. 1 is forexample a drain region, the doped area 116 is for example a gate, andthe doped area 118 is for example a source region. The doped area 120 isfor example a bulk region, The field oxide structure 104 comprises afield oxide layer 104 a, a field oxide layer 104 b and a field oxidelayer 104 c. The field oxide layer 104 a and the field oxide layer 104 bare formed and disposed on a part of the doped area 107. Thepoly-silicon resistor 102 is formed and disposed on the field oxide 104a and the field oxide 104 b.

The poly-silicon resistor 102 comprises a plurality of segments, thesegments are corresponding to a plurality of electrical connectingterminals, such as electrical connecting terminal 102 a, electricalconnecting terminal 102 b and electrical connecting terminal 102 c. Theelectrical connecting terminal 102 b can be used for connecting to aninternal circuit (which has a reference voltage). The electricalconnecting terminal 102 c can be used for connecting to a groundterminal. A divider resistance exist between the electrical connectingterminal 102 b and electrical connecting terminal 102 c. Whenmanipulating the semiconductor structure 10, a gate voltage is appliedto the gate, a drain voltage is applied to the drain and a sourcevoltage is applied to the source. Besides, the electrical connectingterminal 102 b is coupled to a reference voltage, the electricalconnecting terminal 102 c is coupled to a ground terminal with a groundvoltage. Since a divider resistance exists between the electricalconnecting terminal 102 b and the electrical connecting terminal 102 c,a voltage difference exists between the electrical connecting terminal102 b and the electrical connecting terminal 102 c.

In one embodiment, the active area 103 is for example a high voltagedevice. In particular, the active device 103 is for example but notlimited to a n type junction gate field-effect transistor (NJFET). Inone embodiment, the active device 103 can be manufactured by applying alocal oxidation of silicon (LOCOS) process, an EPI process, a non-EPIprocess, a field oxidation (FOX) process, a shallow trench isolation(STI) process, a deep trench isolation (DTI) process and/orsilicon-on-insulator (SOI) process.

The outline of the active device 103 can be circle structures, ellipsestructures or octagon structures or other possible structures. In oneembodiment, a second type conductive buried layer (such as a n typeburied layer) is used for a channel of the NJFET. In one embodiment, then type channel can be formed from n type well, n type drift region, ntype buffer layer and/or n type deep well. The pinch-off voltage of theNJFET can be adjust by adjusting the distance between the n type buriedlayer.

The semiconductor structure 10 combines the poly-silicon 102 and theactive device 103. For example, the poly-silicon resistor 102 isembedded in a field oxide layer of the doped area 107 (such as a driftregion). The volume of the semiconductor structure can be reduced andthe semiconductor structure can be produced by high voltage processwithout additional mask process. Besides, the embedded poly-siliconresistor 102 can be high resistance resistors and can be applied involtage division circuit and voltage reduce circuit.

FIG. 2A illustrates a top view of the semiconductor structure of FIG. 1according to one embodiment of the invention. Referring to FIG. 2A, thepoly-silicon resistor 102-1 is one embodiment of the poly-siliconresistor 102 in FIG. 1. The poly-silicon resistor 102-1 can comprise aplurality of concentric circulars or concentric circles with differentradius of curvature. In other embodiments, the poly-silicon resistor102-1 can be but not limited to octagon structures (such as octagonring-shaped structures), a plurality of half circular structures, aplurality of elliptical circular structures or irregular semicirclestructures. The poly-silicon resistor 102-1 can be formed by firstforming a poly-silicon material on the field oxide layer 104 (shown inFIG. 1) and then patterning the poly-silicon material into the halfcircular structures, the elliptical circular structures, irregularsemicircle structures, the concentric circular structures, theconcentric circle structures or the octagon structures.

Referring to FIGS. 1 and 2A, the doped area 114 of FIG. 1 iscorresponding to the area 1022 (such as the drain region) of FIG. 2A.The area 1022 can comprises a contact. The doped area 116 iscorresponding to the area 1036 (such as the gate region) of FIG. 2A. Thedoped area 118 is corresponding to the area 1034 (such as the sourceregion) of FIG. 2A. The doped area 120 is corresponding to the area 1032(such as the base region) of FIG. 2A.

In this embodiment, the poly-silicon resistor 102-1 can have a pluralityof half circular structures, half-ring shaped structures, irregularsemicircle structures, a plurality of concentric circle structures, aplurality of concentric circular structures or a plurality of octagonsurrounding the drain. The poly-silicon resistor 102-1 has an openingarea 1028. The opening area comprises a plurality of conductivity layer.The conductivity layer can comprise metal segments or poly-siliconsegments for connecting each ring of the poly-silicon resistor 102-1 tothe next ring of the poly-silicon resistor 102-1.

The poly-silicon resistor 102-1 can be electrically connected to theground terminal by a conductive layer 1024 and can be electricallyconnected to the internal circuit (which has a reference voltage) by aconductive layer 1026. The conductive layer 1024 and the conductivelayer 1026 can comprise metal, poly-silicon or other conductivematerials. A part of the poly-silicon resistor 102-1 between theconductive layer 1024 and the conductive layer 1026 can be a dividerresistance. The resistances of the divider resistance and the outmostpart of the poly-silicon resistor 102-1 taking out the dividerresistance can be represent by a ratio relationship. For example, theresistances of the divider resistance is R, the resistances of theoutmost part of the poly-silicon resistor 102-1 taking out the dividerresistance is 100R, the ratio relationship is 1:100.

FIG. 2B illustrates a top view of the semiconductor structure of FIG. 1according to one embodiment of the invention. Referring to FIG. 2B, thepoly-silicon resistor 102-2 is another embodiment of the poly-siliconresistor 102 of FIG. 1. The structure, material, shape, forming methodand manipulating method of poly-silicon resistor 102-2 can be similar tothe structure, material, shape, forming method and manipulating methodof poly-silicon resistor 102-1. The difference between the poly-siliconresistor 102-1 and poly-silicon resistor 102-2 is that the poly-siliconresistor 102-2 having a large metal field plate for reducing theelectric field effect.

FIG. 2C illustrates a top view of the semiconductor structure of FIG. 1according to one embodiment of the invention. Referring to FIG. 2C, thepoly-silicon resistor 102-3 is one embodiment of the poly-siliconresistor 102 in FIG. 1. The poly-silicon resistor 102-3 can comprise aplurality of concentric half circulars or half rings symmetrically ormirror-imagined disposed relative to the area 1022 (such as a drainregion) to arrange into a plurality of circular-liked structures. Thepoly-silicon resistor 102-3 can be formed by ways similar to the methodfor manufacturing the poly-silicon resistor 102-1 of FIG. 2A. Twoneighboring concentric half circulars of the concentric half circularsdisposed at the same side relative to the area 1022 are electricallyconnected by metal, poly-silicon or other conductivity materials.

In this embodiment, the same ring of the poly-silicon resistor 102-3 isequipotential. Besides, the outmost ring of the poly-silicon resistor102-3 can be connected to another poly-silicon resistor 1020 by aconductive layer 1024 a. The poly-silicon resistor 1020 can be furtherconnected to a ground terminal by a conductive layer 1024 b. Therefore,the resistance characteristic of poly-silicon resistor 102-3 can becontrolled more specifically.

The poly-silicon resistor 102-3 shown in FIG. 2C illustrates but notlimited to a concentric circular structures comprising a plurality ofhalf circular with different radius of curvature. In other embodiments,the poly-silicon resistor 102-3 can be elliptical structures, concentriccircle or octagon structures.

FIG. 2D illustrates a top view of the semiconductor structure of FIG. 1according to one embodiment of the invention. Referring to FIG. 2D, thepoly-silicon resistor 102-4 is one embodiment of the poly-siliconresistor 102 in FIG. 1. The poly-silicon resistor 102-4 can comprise anirregular semicircle structures surrounding the area 1022 (such as adrain region). Each ring of the irregular semicircle structures shiftwhen curving so that the layout process can be simpler. In thisembodiment, the voltage potentials of each ring in the irregularsemicircle structures are different. A distance of each ring of thepoly-silicon resistor 102 can be enlarged to prevent the dramaticvoltage drop. Besides, the operation of conductive layer 1024 a, theanother poly-silicon resistor 1020 and the conductive layer 1024 b isused for controlling the poly-silicon resistor 102-4 more specificallyand is described advanced in FIG. 2C.

FIG. 2E illustrates a top view of the semiconductor structure of FIG. 1according to one embodiment of the invention. Referring to FIG. 2E, thepoly-silicon resistor 102-5 is one embodiment of the poly-siliconresistor 102 in FIG. 1. The poly-silicon resistor 102-5 can comprise aplurality of curved concentric circulars or half rings surrounding thearea 1022 (such as a drain region) to arrange into a plurality ofcircular-liked structures. The poly-silicon resistor 102-5 can be formedby ways similar to the method for manufacturing the poly-siliconresistor 102-1 of FIG. 2A. The operation of conductive layer 1024 a, theanother poly-silicon resistor 1020 and the conductive layer 1024 b isused for controlling the poly-silicon resistor 102-5 more specificallyand is described advanced in FIG. 2C.

The poly-silicon resistor 102-5 in FIG. 2E is illustrate as but notlimited to a concentric circular structures. In other embodiments, thepoly-silicon resistor 102-5 can be an elliptical structures or anoctagon ring structure.

Second Embodiment

FIG. 3 illustrates a semiconductor structure according to one embodimentof the invention. Referring to FIG. 3, the semiconductor structure 20comprises a substrate 200, an active device 203 formed in a surface areaof the substrate 200, such as a silicon substrate. The substrate 200 hasa first conductivity, for example a p type conductivity. The activedevice 203 has a doped area 206 a, a doped area 206 b, a doped area 207,a plurality of doped area 208, a doped area 209 a, a doped area 209 b, adoped area 210, a doped area 212, a doped area 214, a doped area 216, adoped area 218 and a doped area 220. The doped area 216 is disposed onthe doped area 206 a. The doped area 206 a is disposed between the dopedarea 207 and the doped area 216.

The doped area 206 a, the doped area 206 b, the doped area 212, thedoped area 216 and the doped area 220 have a first type conductivity,the doped area 207, the doped area 208 the doped area 210, the dopedarea 214 and the doped area 218 have a second type conductivity, thefirst type and the second type conductivities are different. Forexample, the first type conductive doped area are doped with p typeconductive ions and the second type conductive doped area are doped withn type conductive ions.

In one embodiment, the doped area 214, the doped area 216, the dopedarea 218 and the doped area 220 are heavily doped areas having heavilydoped ions. The doped area 206 a, the doped area 206 b, the doped area207 and the doped area 208 are lightly doped areas having light dopedions. In one embodiment, the doped area 206 a and the doped area 206 bare high voltage deep wells having a first type conductivity, such as ptype deep wells. The doped area 207 is a high voltage well, such as ahigh voltage n type well. The doped area 208 is disposed adjacent to thedoped area 206 a. For example, the doped area 208 is disposed at alateral side of the doped area 206 a. The doped area 209 a and the dopedarea 209 b are disposed at the bottom side of the doped area 206 a. Thedoped area 209 a and the doped area 209 b can be n type buried layers. Adistance between the doped area 209 a and the doped area 209 b isrelated to a pinch-off voltage of the active device 203. The doped area210 and the doped area 212 can be similar to the doped area 110 and thedoped area 112.

The field oxide structure 204 comprises a field oxide layer 204 a, afield oxide layer 204 b and a field oxide layer 204 c. The field oxidelayer 204 a and the field oxide layer 204 b are formed and disposed on apart of the doped area 207. The poly-silicon resistor 202 is formed anddisposed on the field oxide layer 204 a and the field oxide layer 204 b,and can comprise the structures of embodiments illustrate in FIGS.2A˜2E. The poly-silicon resistor 202 comprises a plurality of segments,the segments are corresponding to a plurality of electrical connectingterminals, such as electrical connecting terminal 202 a, electricalconnecting terminal 202 b and electrical connecting terminal 202 c. Theelectrical connecting terminal 202 a˜202 c can be similar to theelectrical connecting terminal 101 a˜101 c of FIG. 1.

In one embodiment, the active device 203 is for example a high voltagedevice. In particular, the active device 203 is for example but notlimited to a n type junction gate field-effect transistor (NJFET). Inone embodiment, the active device 203 can be manufactured by processsimilar to process for manufacturing the active device 103 of FIG. 1.The active device 203 can be other semiconductors. In one embodiment,the second type conductive buried layer 209 a and the second typeconductive buried layer 209 b (such as n type buried layers) can be usedas the channel of the NJFET. The pinch-off voltage can be adjusted byadjusting the distance between the n type buried layers.

The semiconductor structure 20 combines the poly-silicon 202 and theactive device 203. For example, the poly-silicon resistor 202 isembedded in a field oxide layer of the doped area 207 (such as a driftregion). The volume of the semiconductor structure can be reduced andthe semiconductor structure can be produced by high voltage processwithout additional mask process. Besides, the embedded poly-siliconresistor 202 can be high resistance resistors and can be applied involtage division circuit and voltage reduce circuit.

Third Embodiment

FIG. 4 illustrates a semiconductor structure according to one embodimentof the invention. Referring to FIG. 4, the semiconductor structure 30comprises a substrate 300, an active device 303 formed in a surface areaof the substrate 300, such as a silicon substrate. The substrate 300 hasa first conductivity, for example a p type conductivity. The activedevice 303 has a doped area 306 a, a doped area 306 b, a doped area 307,a plurality of doped area 310, a doped area 312, a doped area 314, adoped area 318 a, a doped area 318 b and a doped area 320. The dopedarea 318 a and the doped area 318 b are disposed on the doped area 306a. The doped area 306 a is disposed between the doped area 307 and thedoped area 318 a and the doped area 318 b.

The doped area 306 a, the doped area 306 b, the doped area 312, thedoped area 318 b and the doped area 320 have a first type conductivity,the doped area 307, the doped area 310, the doped area 314 and the dopedarea 318 a have a second type conductivity, the first type and thesecond type conductivities are different. For example, the first typeconductive doped area are doped with p type conductive ions and thesecond type conductive doped area are doped with n type conductive ions.

In one embodiment, the doped area 314, the doped area 318 a, the dopedarea 318 b and the doped area 220 are heavily doped areas having heavilydoped ions. The doped area 306 a, the doped area 306 b, the doped area307 are lightly doped areas having light doped ions. In one embodiment,the doped area 306 a and the doped area 306 b are wells having a firsttype conductivity, such as p type wells. The doped area 307 is a highvoltage well having a second type conductivity, such as a high voltage ntype well. The doped area 310 and the doped area 312 can be similar tothe doped area 110 and the doped area 112 of FIG. 1.

The field oxide structure 304 comprises a field oxide layer 304 a, afield oxide layer 304 b and a field oxide layer 304 c. The field oxidelayer 304 a and the field oxide layer 304 b are formed and disposed on apart of the doped area 307. The poly-silicon resistor 302 is formed anddisposed on the field oxide layer 304 a and the field oxide 304 b, andcan comprise the structures of embodiments illustrate in FIGS. 2A˜2E.The poly-silicon resistor 302 comprises a plurality of segments, thesegments are corresponding to a plurality of electrical connectingterminals, such as electrical connecting terminal 302 a, electricalconnecting terminal 302 b and electrical connecting terminal 302 c. Theelectrical connecting terminal 302 a˜302 c can be similar to theelectrical connecting terminal 102 a˜102 c of FIG. 1.

In one embodiment, the active area 303 is for example a high voltagedevice. In particular, the active device 303 is for example but notlimited to a n type laterally diffused metal oxide semiconductor(LDMOS). In one embodiment, the active device 303 can be manufactured byultra high voltage (UHV) process. The doped area 314 can be a drainregion, the gate structure 316 can be a gate region comprises a gatelayer and a gate oxide layer. The doped area 318 a and the doped area318 b can be electrically connected source region and base region. Inother embodiment, the active device 303 can be other semiconductordevices.

The semiconductor structure 30 combines the poly-silicon resistor 302and the active device 303. For example, the poly-silicon resistor 302 isembedded in a field oxide layer of the doped area 307 (such as a driftregion). The volume of the semiconductor structure can be reduced andthe semiconductor structure can be produced by high voltage processwithout additional mask process. Besides, the embedded poly-siliconresistor 302 can be high resistance resistors and can be applied involtage division circuit and voltage reduce circuit.

The semiconductor structures in the embodiments of the invention cancombine the poly-silicon resistor and the active device, and can beapplied to a high voltage semiconductor structure. Therefore, the volumeof the semiconductor structure can be reduced and the semiconductorstructure can be manufacturing by high voltage process withoutadditional mask process. Besides, the embedded poly-silicon resistor 302can be high resistance resistors and can be applied in voltage divisioncircuit and voltage reduce circuit.

While the invention has been described by way of example and in terms ofthe preferred embodiment(s), it is to be understood that the inventionis not limited thereto. On the contrary, it is intended to cover variousmodifications and similar arrangements and procedures, and the scope ofthe appended claims therefore should be accorded the broadestinterpretation so as to encompass all such modifications and similararrangements and procedures.

What is claimed is:
 1. A semiconductor structure, comprising: asubstrate; an active device, formed in a surface area of the substrate,the active device having a first doped area, a second doped area and athird doped area, wherein the second doped area is disposed on the firstdoped area, the first doped area is disposed between the second and thethird doped area, the first doped area has a first type conductivity,the third doped area has a second type conductivity and a drain, thefirst type conductivity and the second type conductivity are different;a field oxide layer, disposed on a part of the third doped area; and apoly-silicon resistor, disposed on the field oxide layer andelectrically connected to the third doped area and coupled to a groundterminal, wherein the poly-silicon resistor comprising at least threeelectrical connecting terminals, the at least three electricalconnecting terminals coupled to the drain, an internal circuit and theground terminal, respectively.
 2. A semiconductor structure according toclaim 1, wherein the first doped area comprises a first light doped areahaving the first type conductivity, the second doped area is a firstheavily doped area having one of the first and the second typeconductivities, and the third doped area comprises a second light dopedarea and a second heavily doped area, the second light doped area andthe second heavily doped area have the second type conductivity.
 3. Asemiconductor structure according to claim 1, wherein the poly-siliconresistor is electrically connected to an internal circuit and a groundterminal, the poly-silicon resistor has a plurality of half-circularstructures, a plurality of elliptical structures, a plurality ofirregular semicircle structures, a plurality of concentric circlestructures or a plurality of octagon structures.
 4. A semiconductorstructure according to claim 3, wherein the second heavily doped area isthe drain, the half-circular structures, the elliptical structures, theirregular semicircle structures, the concentric circle structures or theoctagon structures encircle the drain.
 5. A semiconductor structureaccording to claim 4, wherein the half-circular structures, theelliptical structures or the concentric circle structures comprise aplurality of ring-shaped structures with different curvatures.
 6. Asemiconductor structure according to claim 4, wherein the half-circularstructures comprise a plurality of first concentric half rings withdifferent radius and a plurality of second concentric half rings withdifferent radius, the first and the second half rings are symmetricallydisposed or mirror-imaged disposed relatively to the drain, twoneighboring half rings of the first half rings are electricallyconnected, and two neighboring half rings of the second half rings areelectrically connected.
 7. A semiconductor structure according to claim6, wherein the two neighboring first half rings and the two neighboringsecond half rings are electrically connected by a metal material or apoly-silicon material.
 8. A semiconductor structure according to claim1, further comprising a plurality of buried layers disposed between thefirst doped area and the substrate, wherein the buried layers has asecond type conductivity, and a distance between two of the buriedlayers is related to a pinch-off voltage of the active device.
 9. Asemiconductor structure according to claim 1, further comprising aplurality of fourth doped areas disposed adjacent to the first dopedarea, wherein the fourth doped areas have the second type conductivity,and a distance between the fourth doped areas is related the a pinch-offvoltage of the active device.
 10. A semiconductor structure according toclaim 9, wherein the second doped area is coupled to a gate voltage, anda part of the fourth doped areas is coupled to a source voltage.